Add manual build option

Signed-off-by: R. Miles McCain <github@sendmiles.email>

.github/workflows/build-docker-manual.yml

@@ -0,0 +1,43 @@
+name: Build release Docker images
+
+on:
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Docker image tag'  
+jobs:
+  publish_to_docker_hub:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      
+      - name: Prepare tags
+        id: prep
+        run: |
+          DOCKER_IMAGE=milesmcc/shynet
+          TAGS="${DOCKER_IMAGE}:${{ github.event.inputs.tag }}"
+          echo ::set-output name=tags::${TAGS}
+          
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+        
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_TOKEN }}
+
+      - name: Build and push advanced image
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          push: true
+          tags: ${{ steps.prep.outputs.tags }}